MEAN HIGH WATER


Flooding & Sea Level Rise in the SC Lowcountry





ABOUT
Mean High Water (MHW) is a project documenting the impacts of sea level rise & flooding in and beyond the South Carolina Lowcountry. The title is in reference to the MHW tidal datum defined and maintained by the NOAA Center for Operational Oceanographic Products and Service.

The tides of Charleston Harbor and the Atlantic Ocean are increasingly encroaching into the natural and built environment of Charleston and the Lowcountry. The rate of increase in the number of coastal flood events is alarming. Approximately 45% of all coastal floods observed in Charleston Harbor from 1953 through 2020 have occurred since 2010. An average of 18.8 coastal floods occurred per year in the 1990s. In the 2010s, the annual average was 42.4 coastal floods2, an increase of over 200%.

MHW was started in 2020 by photographer and engineer Jared Bramblett. It is intended to be an evolving and collaborative documentation of the impacts of flooding. If you are interested in participating and submitting to the project, please reach out. All content on this site is copyrighted. If you are interested in using any content, please submit a request.


CONTACT
Jared Bramblett
jaredbramblett@gmail.com

︎ ︎ ︎  
All thoughts and opinions presented on this site are solely those of the author and are not necessarily those of any other organizations.


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RECORDS & STATISTICS
Charleston Harbor, Cooper River Entrance1

Coastal Floods (>7-ft MLLW)2
1.
2.
3.
4.
5.
89 (2019)
68 (2020)
58 (2015)
55 (2016)
46 (2017, 2021)

Major Coastal Floods (>8-ft MLLW)2
1.
2.
3.
4.
5.
7 (2020)
6 (2015)
4 (2021)
4 (2019)
3 (2018)

Peak Tide Crests (MLLW)3
1.
2.
3.
4.
5.
09/22/1989 - 12.52-ft (Hugo)
08/11/1940 - 10.23-ft (Unnamed)
09/11/2017 - 9.92-ft (Irma)
10/08/2016 - 9.29 (Matthew)
01/01/1987 - 8.81-ft 

26 of the 40 (65%) major flood tides on record have occurred since 2015.3

Statistics current as of 07/01/2022


REFERENCES

1Tidal Benchmark Station - Charleston, Cooper River Entrance, SC - Station ID: 8665530

2NWS Coastal Flood Event Database

3Advanced Hydrologic Prediction Service, Charleston, SC 

A Game of Inches

September 15 & 16, 2020



We’re in the middle of a ‘king tide’ cycle on the southeast coast, and the tides have been running roughly 1-1.5 feet higher than NOAA predictions (although almost exactly matching the NWS Advanced Hydrologic Prediction Service) in Charleston Harbor. The peaks of the high tides have occured during the evening the past two nights, which allowed me two opportunities to observe and document them. On 9/15, I biked around the Charleston Peninsula, and on 9/16, I remained on Lockwood Drive adjacent to the Ashley River through the peak of the tide.

The behavior of the tides seems to vary with each event, particularly due to the weather and the winds, and the peak tide observed at the Customs House appears to have occured 20 to 30 minutes after the predicted peak. The behavior of the tides also vary among the river systems, with the Ashley River peaking later than the Cooper River right now. The tides peaked at 8.09 and 7.92 feet MLLW on 9/15 and 9/16, respectively. While this may not seem like a substaintial difference (only 0.17-feet), the impacts along the developed land of the Peninsual are significant. Charleston really is a city at sea level, and these king tides show that it’s a game of inches as to the severity of the flooding from these tides. Thankfully, there was no significant rainfall around the peak of these tides.

© 2022